'Not much break, pretty straight putt,' said Han, who wins for the second time this season.
Han finished regulation tied with Ward at 17-under-par 199 after both players put together phenomenal rounds. The fine play continued in the extra session and Ward found herself with a chance to win at the first playoff hole.
Ward hit her approach to five feet at the par-4 18th while Han missed the green. However, Ward missed the birdie try and Han got up and down for par to extend the playoff.
'I felt like I should have made that putt on the first playoff hole,' said Ward, who won this event in 2001. 'It was late in the day, and I didn't hit the place I needed to.'
On the second playoff hole, the par-4 10th, the tables were turned as Han dropped her second shot inside four feet and Ward missed the putting surface with her approach. Ward wasn't out of it yet, however, and converted the long birdie putt from off the green. Han then rolled her putt in for a birdie of her own.
The duo headed back to the par-3 17th, where Han made a late bogey to lose the outright lead in regulation, to play a third extra hole. Ward hit her approach within 20 feet while Han left herself with a longer putt for birdie.
Han calmly ran home the putt and, after Ward missed her birdie try left, the victory belonged to the South Korean.
'This whole three days, I hit pretty straight and my irons were pretty good and so was my putting,' said Han, who shot a 66 in the final round. 'It's all good actually.'
Han, the runner-up at this event last year, held a share of the lead to start the final round and jumped out of the gate with back-to-back birdies from the first to assume the top spot. She added an eagle at the par-5 fourth and reached 16 under at the fifth after her second shot landed six feet from the cup.
The 25-year-old kept things rolling with a birdie at the ninth and reached 18 under with a birdie at the 11th. Han found trouble with a bogey at the 12th but countered with a birdie at the following hole.
It wasn't until the bogey at the 17th that Han was met by Ward.
Ward was on fire early on with five birdies and an eagle on the front nine to go out in 29.
She picked up a birdie at the 11th but dropped a shot at the 14th. Ward then birdied the 15th and hit her tee shot to five feet at the 17th to join Han in the lead.
'I didn't want to get too far ahead of myself,' said Ward, who fired a 63 on Sunday. 'I had to get the putts to drop at the right time and gain some momentum.'
Michele Redman finished two shots back at 15-under-par 201 after a round of 67. Juli Inkster posted a 66 to finish alone in fourth place at 12-under-par 204.
Candie Kung, who shared the 54-hole lead with Han, managed a round of even-par 72 to finish alone in fifth place at 11-under-par 205.